The present invention generally relates to centrifuges, and more specifically, but not exclusively, concerns a centrifuge system that is able to shutoff fluid to the centrifuge when the centrifuge rotor is missing or when the wrong rotor is installed.
Diesel engines are designed with relatively sophisticated air and fuel filters (cleaners) in an effort to keep dirt and debris out of the engine. Even with these air and fuel cleaners, dirt and debris, including engine-generated wear debris, will find a way into the lubricating oil of the engine. The result is wear on critical engine components and if this condition is left unsolved or not remedied, engine failure. For this reason, many engines are designed with full flow oil filters that continually clean the oil as it circulates between the lubricant sump and engine parts.
There are a number of design constraints and considerations for such full flow filters, and typically these constraints mean that such filters can only remove those dirt particles that are in the range of 10 microns or larger. While removal of particles of this size may prevent a catastrophic failure, harmful wear will still be caused by smaller particles of dirt that get into and remain in the oil. In order to try and address the concern over small particles, designers have gone to bypass filtering systems which filter a predetermined percentage of the total oil flow. The combination of a full flow filter in conjunction with a bypass filter reduces engine wear to an acceptable level, but not to the desired level. Since bypass filters may be able to trap particles less then approximately 10 microns, the combination of a full flow filter and bypass filter offers a substantial improvement over the use of only a full flow filter. Centrifuges, both self-driven and externally driven types, are routinely used for bypass filtering because of their ability to remove small particles from fluids like oil as well as other types of fluids.
A typical hydraulically-driven (Hero-turbine) centrifuge rotor is driven by the reaction force from one or more tangentially-oriented orifice jets. The orifices also serve to throttle or limit the flow rate through the rotor, since a bypass device must not be allowed to divert excessive flow back to the sump, which is typically 5-10% of pump outlet flow, maximum. If an operator inadvertently forgets to replace the centrifuge rotor during service, or installs an incorrect rotor with larger jets, the diverted bypass flow may be excessive, causing low oil pressure and associated engine wear.
Centrifuge systems have been proposed that automatically shutoff fluid flow when the rotor is not installed, but these systems have a number of drawbacks. For example, a centrifuge system has been proposed that has an outer sleeve slidably received around a shaft that supplies fluid to the centrifuge via openings in the shaft. Oil pressure or a spring is used to axially bias the sleeve so that it covers the openings in the shaft when the rotor is removed. However, such a system fails to prevent a wrong rotor from being installed, and due to its location, the sleeve can be easily damaged or tampered with so that it is rendered inoperable. Further, the relatively thin sleeve is hard to actuate. This type of system also has a number of detrimental affects on performance. Axially biasing the sleeve applies an axial load on the thrust surfaces of the bearings in the centrifuge, which in turn increases friction as well as wear. Bearings in centrifuges are normally very sensitive to any thrusting axial loads. Further, since the sleeve is not located on the axis of the centrifuge, but around the axis, a torque load is created that tends to slow the centrifuge's speed.
Thus, there is a need for improvement in this area of technology.